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Dead A/C

Discussion in 'General Chevy & GM Tech Questions' started by ct9a, Jul 28, 2008.

  1. ct9a

    ct9a New Member 1000 Posts

    Ok, so my I bought my truck knowing that the A/C doesn't work , but I'm taking a trip to TX next month and I need it!

    My first thought was to check the freon levels, they were slightly low, but not empty, so I filled it up. No go. I filled the system with freon to the higher levels of the tolerance and still no go, but something did happen when I did this: The compressor started to engage and disengage every couple of seconds, previously, it had not engaged at all. When it engages, the pressure drops way down, then the pressure shoots way up when it disengages. Is the constant engage/disengage normal? Perhaps this is what the problem with the A/C is?

    I've checked the pressure levels through out the day yesterday and today, and have seen no drop in pressure, so I'm ruling out leakages. Maybe the canister needs more freon oil?

    Any suggestions are appreciated. My Haynes manual says to take it to the shop :rolleyes:
  2. collinsperformance

    collinsperformance New Member

    these are simple if you break the system down.
    yes the compressor should kick in and out farly often.
    you checked the level and it is good. can you feel one AC line getting cold or see it sweat? if so then the freon is cycling if not you might have a plug somewhere.
    now if the flow is flowing then your heator / blend door motor is not moving to allow the cool air in. test the motor and or replace.
    you do hear the fan motor running correct?
    mike
  3. ct9a

    ct9a New Member 1000 Posts

    From what you're saying, it sounds like a clog. None of the lines get colder or create condensation on them.

    I'm fairly fure the blend door is fine, when I turn the heat all the way up I can definitely feel the difference. And the fan motor seems to work fine at all adjustment points between low and high.

    Guess it's time to take it to someone to have it looked at. :grrrrrr:
  4. GaryL

    GaryL New Member Platinum Contributor 1000 Posts

    You want the low pressure side to stay between 40-46 psi when the compressor is engaged. There is a low pressure switch that cuts the compressor off when the pressure gets below 20 or so psi. Set the a/c to max, cold and high fan and fill until it will hold steady while engaged. The high side should be in the 250 +/- range.

    Don't worry about needing an a/c here in Texas, it was a nice cool 107 at my house yesterday. The hot weather won't be here until late August.
  5. ct9a

    ct9a New Member 1000 Posts

    Oh hell, I'm a Colorado boy born and raised. I get uncomfortable when temps reach the 80's. 100+ is a killer for me.
  6. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts

    Excellent information. I'm always just eyeballing the pressures without knowing exactly where I should be... I just watched the pressures to make sure it wouldn't take anymore and the air coming out was cold...oops..
  7. ct9a

    ct9a New Member 1000 Posts

    Gary, thanks for the tips and info. I went out and looked at the pressure again, and while the pressure was high without the compressor on, it dropped to ~25psi when it was engaged. Put some more freon in and I've got cool air! Not quite cold and it looks like I'll need another bottle, so hopefully this takes care of it.
  8. GaryL

    GaryL New Member Platinum Contributor 1000 Posts

    Great news!! Where are you going in Texas?
  9. ct9a

    ct9a New Member 1000 Posts

    We're leaving Denver the night of the 17th of Aug. (Sunday) and will stop in Amarillo on Monday. Then Tuesday night we'll be leaving Amarillo and heading for Dallas for a few days then turning around and making the same trip with a couple of days in Amarillo. Wife has family in both cities.
  10. GaryL

    GaryL New Member Platinum Contributor 1000 Posts

    When you come through Lewisville on I-35E, you'll be about 13 miles from me, be sure and wave.:meuh:

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